Sökning: "geometric distortions"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden geometric distortions.

  1. 1. Quality assurance for magnetic resonance imaging (MRI) in radiotherapy

    Författare :Mary Adjeiwaah; Tufve Nyholm; Rob HN Tijssen; Umeå universitet; []
    Nyckelord :MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; MEDICIN OCH HÄLSOVETENSKAP; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; MEDICAL AND HEALTH SCIENCES; Magnetic resonance imaging; Radiotherapy; geometric distortions; patient-induced susceptibilities MR-only; radiofysik; radiation physics;

    Sammanfattning : Magnetic resonance imaging (MRI) utilizes the magnetic properties of tissues to generate image-forming signals. MRI has exquisite soft-tissue contrast and since tumors are mainly soft-tissues, it offers improved delineation of the target volume and nearby organs at risk. LÄS MER

  3. 2. Quality assurance for magnetic resonance imaging (MRI) in radiotherapy

    Författare :Mary Adjeiwaah; Tufve Nyholm; Anders Garpebring; Joakim Jonsson; Sofie Ceberg; Umeå universitet; []
    Nyckelord :MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; magnetic resonance imaging; MRI; radiotherapy; RT; geometric distortions; magnetic susceptibility; B0 maps; quality assurance; radiofysik; radiation physics;

    Sammanfattning : The use of Magnetic Resonance Imaging (MRI) in the radiotherapy (RT) treatment planning workflow is increasing. MRI offers superior soft-tissue contrast compared to Computed Tomography (CT) and therefore improves the accuracy in target volume definitions. LÄS MER

  4. 3. Geometric Models for Rolling-shutter and Push-broom Sensors

    Författare :Erik Ringaby; Per-Erik Forssén; Tomáŝ Pajdla; Linköpings universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Almost all cell-phones and camcorders sold today are equipped with a  CMOS (Complementary Metal Oxide Semiconductor) image sensor and there is also a general trend to incorporate CMOS sensors in other types of cameras. The CMOS sensor has many advantages over the more conventional CCD (Charge-Coupled Device) sensor such as lower power consumption, cheaper manufacturing and the potential for onchip processing. LÄS MER

  5. 4. Geometric Computer Vision for Rolling-shutter and Push-broom Sensors

    Författare :Erik Ringaby; Per-Erik Forssén; Anders Heyden; Linköpings universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; rolling shutter cmos video rectification stabilisation push-broom kinect;

    Sammanfattning : Almost all cell-phones and camcorders sold today are equipped with a CMOS (Complementary Metal Oxide Semiconductor) image sensor and there is also a general trend to incorporate CMOS sensors in other types of cameras. The sensor has many advantages over the more conventional CCD (Charge-Coupled Device) sensor such as lower power consumption, cheaper manufacturing and the potential for on-chip processing. LÄS MER

  7. 5. Global Shape Description of Digital Objects

    Författare :Ola Weistrand; Christer Kiselman; Gunilla Borgefors; Örjan Smedby; Michael Floater; Uppsala universitet; []
    Nyckelord :Applied mathematics; shape description; shape approximation; surface parameterization; digital object; spherical harmonics; digital surface; digital image; Tillämpad matematik;

    Sammanfattning : New methods for global shape description of three-dimensional digital objects are presented. The shape of an object is first represented by a digital surface where the faces are either triangles or quadrilaterals. LÄS MER